The IPCC assumed that strong positive feedbacks dominated, and thus arrived at numbers that implied that feedbacks added an additional 2-4 degrees to the 1 degree from CO2 directly. So in the IPCC numbers, at least two thirds of the future warming comes not from the basic greenhouse gas effect but a second independent theory that the Earths climate is dominated by strong positive feedbacks. Other more alarmist scientists have come up with feedback numbers even higher. When Al Gore says that we will see a tipping point where temperatures will run away, he is positing that feedbacks will be nearly infinite (a phenomenon we can hear with loud feedback screeches from a microphone).

But the science of this positive climate feedback theory is far from settled. Just as skeptics are probably wrong to question the basic greenhouse gas effect of CO2, catastrophic global warming advocates are wrong to over-estimate our understanding of these feedbacks. Not only may the feedback number not be high, but it might be negative, as implied by some recent research, which would actually reduce the warming we would see from a doubling of CO2 to less than one degree Celsius. After all, most long-term stable natural systems (and that would certainly describe climate) are dominated by negative rather than positive feedbacks.

What is the physical theory behind the greenhouse gas effect, and can it be computed from the laws of physics? The answer is a resounding yes! The effects of heat trapping by greenhouse gases was first noted over a century ago and understood from the viewpoint of classical physics involving the absorption and emission of electromagnetic radiation by matter and the thermodynamics of gas. The mathematical and physical laws of the interaction of electromagnetic radiation and matter underlie our understanding of greenhouse gas warming.

This understanding gained a firm basis with the development of quantum mechanics in the 1920s. This development enabled detailed calculations of the physics of absorption, scattering, and emission of electromagnetic radiation by atoms and molecules that make up Earth&#8217;s atmosphere. Highly sophisticated radiation transfer codes have been perfected to calculate the energy balance in an atmosphere as energy is transferred through atmospheric layers. Trace polyatomic molecules such as water vapor, CO2, and methane have rotation, bending, and vibration degrees of freedom, and are quite effective at intercepting infrared radiation radiated by Earth&#8217;s surface and the atmosphere.

When a greenhouse molecule absorbs an infrared photon, the molecule rotates or vibrates faster and is said to be in an &#8220;excited&#8221; state. At low gas densities, an excited greenhouse gas molecule will spontaneously (by the rules of quantum mechanics) reradiate an infrared photon, which may escape the atmosphere into space and produce no net warming.

At the higher densities of Earth&#8217;s atmosphere, the excited molecule will bump into (collide with) another molecule (any molecule in the atmosphere). In the collision, the energized greenhouse gas molecule loses its rotational energy, which is transferred to the kinetic energy of the molecule it collides with (this is called collisional de-excitation). The increased kinetic energies of the colliding molecules means that the molecules are moving faster than they were prior to the collision, and the increased velocities of such molecules represents a direct measure of increased atmospheric temperature.

&#8220;Greenhouse gas&#8221; warming occurs because the collisional de-excitation time for greenhouse molecules in Earth&#8217;s lower atmosphere is much shorter than the radiation lifetime of excited molecular states. This is the basic science of greenhouse gas warming, and can be computed from the laws of physics and demonstrated and measured in laboratory experiments. There is no doubt about the efficacy of the science behind greenhouse gas warming (see YouTube video).

In summary, many criticisms of global warming models are specious and fail to reflect an understanding of the basic science behind the models and the extensive history of the development of radiation transfer codes in modeling planetary and stellar atmospheres. Some contrarians engage in arguments that the warming observed is due to &#8220;natural&#8221; mechanisms that have been in play for millions of years. Such proposals should be required not only to identify the specific natural mechanisms in question, but quantify them and present observational or experimental evidence that the mechanisms play a role on a time scale of the past 150 years. Such proposals also ignore the fact that proxy geochemical data show strong support for the conclusion that CO2 increases have played the largest role in explaining these past intervals of global warmth!

Most important, contrarians must show why the scientific basis of greenhouse gas warming is incorrect. It remains unfortunate that the opinions of a handful of contrarians should be given the same weight in the press and the popular media as the studied conclusions of thousands of scientists. This reinforces the general perception that the &#8220;science&#8221; of global warming is uncertain, and provides fodder for some (but by no means all) business and political factions to question the reality of anthropogenic global warming.

In summary, many criticisms of global warming models are specious and fail to reflect an understanding of the basic science behind the models and the extensive history of the development of radiation transfer codes in modeling planetary and stellar atmospheres. Some contrarians engage in arguments that the warming observed is due to &#8220;natural&#8221; mechanisms that have been in play for millions of years. Such proposals should be required not only to identify the specific natural mechanisms in question, but quantify them and present observational or experimental evidence that the mechanisms play a role on a time scale of the past 150 years. Such proposals also ignore the fact that proxy geochemical data show strong support for the conclusion that CO2 increases have played the largest role in explaining these past intervals of global warmth!

Most important, contrarians must show why the scientific basis of greenhouse gas warming is incorrect. It remains unfortunate that the opinions of a handful of contrarians should be given the same weight in the press and the popular media as the studied conclusions of thousands of scientists. This reinforces the general perception that the &#8220;science&#8221; of global warming is uncertain, and provides fodder for some (but by no means all) business and political factions to question the reality of anthropogenic global warming.

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There has been a warming trend ongoing for about 2000 years with a brief interruption by the LIA.

We know the the warming was happening and we know that the warming is happening.

We know what caused the interruption.

Without the LIA, the warming trend is pretty consistent and pretty steady.

The interruption by the LIA caused a pause in the warming, but did not stop it.

It seems very reasonable to accept that whatever it was that caused the warming to run up for 1200 years before the LIA simply resumed when the effects of the Maunder Minimum ended.

I don't see the warming following the Maunder Minimum as a sudden reversal of a previous trend, but rather as a resumption of a trend that was merely interrupted.

By removing the cooling effects of the Maunder Minimum, all of the factors that had been causing the warming of the previous 1200 years resumed and the planet returned to the same level it would have reached had the Maunder Minimum never occurred.

I get it just fine...Goebbels warming an amalgamation of Luddism, misanthropy and Malthusian declinism.

Same self-loathing, different wrapper.

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Fact-filled?

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Yup.

If you were to bother yourself to understand the thematic structure behind Luddism, misanthropy and Malthusian declinism, you'll discover the same doomsday scenarios....But I'm not holding my breath that you would.

I get it just fine...Goebbels warming an amalgamation of Luddism, misanthropy and Malthusian declinism.

Same self-loathing, different wrapper.

Click to expand...

Fact-filled?

Click to expand...

Yup.

If you were to bother yourself to understand the thematic structure behind Luddism, misanthropy and Malthusian declinism, you'll discover the same doomsday scenarios....But I'm not holding my breath that you would.

Click to expand...

That's "buzzword-filled". To be fact-filled, you'd actually have to put some facts in the post. Nice try, not biting.

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